This paper presents a novel method to simulate multiple contacts of deformable objects modeled by the finite-element
method. There have been two main approaches for contact models in the literature. The penalty method fails to guarantee
the non-penetration condition. In the constraint method, imposition of multiple position constraints on arbitrary points of
the surface, caused by the multiple contacts, can be non-deterministic depending on the contact configurations. Infinite
number of solutions exists in most cases. The proposed method uses a deformable membrane of mass and spring to
determine the initial position constraints to obtain a unified solution regardless of the contact configurations. The
membrane is locally generated at the contact region, and is identical to the local triangular surface meshes of the finite-element
model. The membrane is then deformed by the contacts caused by rigid objects such as surgical tools.
Displacements of the mass points of the deformed membrane at the equilibrium state are, then, applied to the finiteelement
model as the position constraints. Simulation results show satisfactory realism in the real-time simulation of the
deformation. The proposed method prevents penetration of the rigid object into the deformable object. The method can
be applied to interactions between tools and organs of arbitrary shapes.
This paper discusses the methods for real-time rendering of time-varying dynamic fluoroscope images including fluid
flow for the ERCP (Endoscopic Retrograde Cholangiopancreatography) simulation. A volume rendering technique is
used to generate virtual fluoroscopy images. This paper develops an image-overlaying method which overlaps the timevarying
images onto the constant background image. The full size fluoroscopy image is computed from the initial
volume data set during the pre-processing stage, which is then saved as the background image. Only the time-varying
images are computed from the time-varying volume data set during the actual simulation. This involves relatively small
computation compared with the background image. The time-varying images are then overlaid onto the background
image to obtain the complete images. This method reduces computational overhead by removing redundant
computations. A simplified particle dynamics model is employed for fast simulation of the fluid flow. The fluid model, a
collection of particles, interacts only with the ducts based on principles of a complete elastic collision. Hence, the
velocity of the particles, when they collide with the duct, can be computed by using simple algebraic equations. The
methods are implemented for fast simulation of the ERCP.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.